Filters



R. J. STEVENS FILTERS Feb. 27, 1968 4 Sheets-Sheet 1 Filed April 8, 1965 FIG. ID

/ VENTOR M f BY A7 RA/[YS Feb. 27, 1968 R. J. STEVENS 3,370,713

FILTERS Filed April 8, 1965 4 Sheets-Sheet 2;

//VVENTOA Feb. 27, 1968 R J, STEVENS 3,370,713

FILTERS Filed April 8, 1965 4 Sheets-Sheet is R. J. STEVENS FILTERS Feb. 27, 1968 Filed April 8, 1965 4 Sheets-Sheet 4 INVENTOR United States Patent 3,370,713 FILTERS Ronald John Stevens, 30, Coombe Lane West, Kingston-upon-Thames, Surrey, England Filed Apr. 8, 1965, Ser. No. 446,675 8 Claims. (Cl. 210-488) ABSTRACT OF THE DISCLOSURE This invention provides an edge type filter comprising in combination laminae arranged in the form of a pack. Apertures in each laminae etched by an electrolytic process, the apertures in alternate laminae aligning throughout the thickness of the pack to form inlet and outlet flow lanes. Bars between the apertures of each lamina of the same thickness as that of the lamina, the bars of alternate laminae aligning throughout the thickness of the pack and crossing the apertures in the intervening laminae thereby forming lateral flow passages. An apertured masking plate at each of two opposite sides of the pack, the apertures in one masking plate communicating with alternate inlet flow lanes and the apertures in the other plate leading to the intervening outlet fiow lanes so that the liquid to be filtered is caused to flow through the flow passages and then into the outlet flow lanes, the filtered fluid then passing through the apertures in the other masking plate for utilization.

The foregoing abstract is not intended to be a comprehensive discussion of all of the principles, possible modes or applications of the invention disclosed in this document and should not be used to interpret the scope of the claims which appear at the end of this specification.

This invention relates to filters for fluids, gaseous or liquid.

Filters formed from gauze or woven material have the disadvantage that they lack strength especially where the finer'meshes are concerned. Further, accuracy in the size of mesh aperture is difiicult to achieve due to limitations imposed by the manufacturing process involved. In the instance of a woven wire mesh filter, it is obvious that, with the reduction of the gauge of the wire for the finer meshes, a corresponding loss of strength results. Thus, there are practical limitations to the use of woven wire for a filter. Such filters are also liable to become contaminated and, since they are not easily cleaned, they have to be discarded and replaced by new filters.

An object of this invention is to provide a filter for fluids, gaseous or liquid, which avoids the disadvantages of the woven type filter, as previously mentioned, and which has flow channels and perforations that are extremely accurate in size no matter how small they may be, the filter being able to resist any pressure or impact to which it may be subjected.

According to this invention a filter for fluid, gaseous or liquid, comprises a pack of metallic laminae, each lamina having openings which are formed by an etching or electrolytic process, the openings forming filter lanes extending through the thickness of the pack.

More particularly, a filter according to the invention comprises metallic laminae in the form of a pack, alternate or certain of the layers of the pack having openings which coincide throughout the thickness of the pack to form fiow lanes, means for closing alternate flow lanes at opposite faces of the pack, the flow lanes open at one of 'the said faces being closed by the said means at the other e such that fluid to be filtered passes into the flow lanes 3,370,713 Patented Feb. 27, 1968 opening into one face of the pack, through the lateral passages and out through the flow lanes opening into the other face of the pack.

In order that the invention may be clearly understood it will now be described more fully, by Way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a fragmentary view of a lamina for use in a filter pack according to the invention;

FIGURE 2 is a detail section through two of the flow lanes in the filter pack, the section being drawn to an enlarged scale;

FIGURE 3 is an enlarged fragmentary view of two laminae, one lamina being superposed on the other and showing openings in one lamina displaced relatively to those in the other lamina;

FIGURE 4 is a section on line IV--IV of FIGURE 3;

FIGURE 5 is an enlarged fragmentary view 'of a masking plate for flow lanes;

FIGURE 6 is an elevation, partly in section, of a mounting and clamping device for filter packs of rectangular shape;

FIGURE 7 is a side elevation thereof;

FIGURE 8 is a section on line VIIIVIII of FIG- URE 6;

FIGURE 9 is a fragmentary view of a lamina for interleaving between laminae shown in FIGURE 1;

FIGURE 10 is an enlarged fragmentary view of the lamina shown in FIGURE 9 superposed on the lamina shown in FIGURE 1;

FIGURE 11 is a fragmentary view of a circular filter pack according to the invention, showing portions of the laminae;

FIGURE 12 is an elevation, partly broken away, of a circular filter assembly;

FIGURE 13 is a plan of a channel unit for use with circular filter packs, the channels having openings outwardly of the unit;

FIGURE 14 is a side elevation thereof;

FIGURE 15 is a plan of a channel unit for use with circular filter packs, the channels having openings inwardly of the unit;

FIGURE 16 is a side elevation thereof; and

FIGURE 17 is a diagram of a filter arrangement according to the invention.

Referring to the drawings, laminae for the filter pack may be formed from rolled metallic foil of any desired thickness, for example 0.003 inch cut into sheets as indicated at 1. Printed on each sheet by lithography, process arts, screen printing or by any other convenient means is a resist pattern as indicated in FIGURE 1, for example. The sheet is then subjected to an etching process as for instance, that disclosed in my British Patent No. 721,592. After etching, a perforated sheet is produced, it being preferred that the perforations should form a pattern as shown in FIGURE 1. The perforations, indicated at 1A be square or oblong. Suitable dimensions for the oblong perforation shown may be 0.200 inch x 0.033 inch. Each perforation, along its long sides, may be separated from adjacent perforations by strips of foil 0.033 inch and along its narrow sides by strips of foil 0.050 inch hereinafter referred to simply as bars. A convenient size for each sheet may be 9 inches long X 5 inches wide, the pattern of perforations being surrounded by a margin inch wide.

Any desired number of sheets each as described are laid one upon another to form a pack, as indicated at 2, FIGURE 2, and in order that the sheets may register one with another holes 2A are provided which receive locating and clamping studs as will later be described. Thus, a filter mesh or virtually any size or any desired pattern can be very easily produced. It is to be understood that the perforations need not necessarily be rectangular and may flow lanes 3 for the fiuid to the filtered. In order to prevent clogging of the lanes by material in the fluid, the first sheet, or first few sheets 3A of the pack facing the direction of flow of the liquid, indicated by arrows in FIGURE 2, may have their apertures reduced in size as indicatedat 3B, the reduced perforations being regularly related in size to that of the other perforations.

In another construction of filter according to the invention, a fiiter pack is composed of perforated sheets having rectangular perforations which may be as shown in FIGURE 1. In this construction of filter pack alternate sheets are displaced in the direction of the arrow A, FIGURE 3, so that two flow lanes 4 and 4A in the'thickness of the pack are formed in place of a single flow 7 lane 3 as shown in FIGURE 2. The bars bordering the narrow side of each perforations are indicated at 4B and it will be seen by reference to FIGURE 4 that the corresponding displacement of the bars 4B has the result that lateral fiow passages 4C are formed between the bars 4B of the sheets of foil immediately above and below a sheet as shown in FIGURE 4. Assuming that the width of each rectangular perforation 1 is 0.200 inch, then the dimensions of each flow pasage 4C will be 0.200 inch 7 X 0.003 inch, that is assuming the thickness of the foil to be 0.003 inch.

' filter pack via the flow lanes 4 then, since the opposite end of each flow lane 4 is closed'by the plate 5A, the fluid will flow through the laternal flow passages 4C into the flow lanes 4A and out through the apertures SC in the masking plate 5A. It will be apparent that for each rectangular perforation 1A of a sheet of foil there will be two flow passages totaling 0.400 inch X 0.003 inch.

In one example of filter pack according to the invention there may be 66 rows of flow lanes in the length of a sheet and columns of flow lanes in its width, alternate rows of lanes forming in-fiow channels and the intermediate rows forming out-flow channels. It will be understood that filtering is effected by the inflow channels. Since each rectangular perforation 1A of each sheet has two bars 413 each 0.200 inch long it will be apparent, on referring to FIGURES 3 and 4, that each sheet of the pack provides a length of edge filter as follows:

66 x 20 X 0.400/2=26.4 inches In a filter pack comprising 200 sheets there is thus 26.400 inch length of edge filter and, assuming that the thickness of each sheet is 0.003 inch, then a total filtering area of 79.2 sq. in., is provided accommodated in a thickness of pack of 0.6 inch. In an area of pack say 9.5 inches x 6 inches, 79.2 sq. in. of filtering area would be equivalent to a very large area of wire gauze.

A suitable mounting and clamping device for two rectangular filter packs is shown in FIGURES 6, 7 and 8. The device comprises a circular flanged plate 6 adapted to fit in a pipe 6A or a suitable container. The plate 6 has a rectangular hole 6B for the discharge of the fluid. Fixed to the plate 6 are side plates 6C connected by a closure 'plate 6D and disposed between the side plates are pairs of equally spaced bars 6B, the bars forming inner grids 6] on two opposite sides of the device as shown in FIGURE 8. A suitable thickness for each bar is 0.050 inch. The spacing of the bars may be effected by washers 6F mounted on rods 6G fixed to the side plates 6C by nuts 6H. Avrectangular filter pack 7, similar tp that previously described, is positioned against the outside of each inner grid 6], the packs being located .by threaded studs 7A inserted through blocks 7B fixed to the grids. Exteriorly of each pack is an outer grid 6K which is similar to the inner grids and which has its bars coincident with those of the inner grids, the outer grids 6K also being located by the studs 7A. The studs project through the holes 2A in the packs and are furnishedwith nuts 7C whereby the filter packs are firmly clamped between their respective inner and outer grids. It will be seen that fluid to be filtered passes into the device by way of a port 7D in the pipe or container 6A through'the filter packs and into the grids whence it passes, after filtration, through the discharge holes 6B. It will be seen that, since the edges of the bars of the grids are arranged in the direction of flow of the fluid, a very strong strueture'is provided capable of resisting pressure. a i

It will be apparent that a relatively small size pressure vessel is required for very large filter area provided by the filter packs, such packs being accommodated in. T or ordinary pipe elements. t p a The mounting and clamping device described provides for two rectangular filter packs, but his to be understood that the device may be modified to enablethe mounting of more than two filter packs. I V

In another construction of filterpack according to the invention, alternate laminae may have lozenge shaped perforations 8 as indicated in FIGURE 9. When such laminae are interleaved between laminae as shown-in FIGURE 1, alternate rows of flow lanes 8A and 8B are formed as indicated in FIGURE 10. As in theconstruc-,

tion of filter pack previously described, alternate rows of flow lanes are closed by a masking plate atone side of the pack and alternate rows by a masking plate at the centrically the perforations being separated ,by bars. 9B. 7

If desired, the perforations in the laminaeinterposedlb'etween the laminae may be displaced as previously described in order to provide lateral flow passages, but:it is preferred that laminae as shown at 9C having lozenge shaped perforations 9D should'be used. As in the instance of the rectangular filter pack, masking plates 9E' and 9F having perforations 9G close alternate concentric.

rows of perforations in order to provide in-flow and out flow lanes. 7

A suitable mounting for circulartype filter shown in FIGURES 12 to 16 inclusive.

The mounting comprises a plurality of axially aligned channel units 10, 10A, 10B, 10C and 10D, FIGURE 12, each having the same diameter as that of the filterpacks. Sandwiched between the channel units are filter packs 10E. The channel units 10A and 10C are identical, one of the units being shown in FIGURES 13 and 14. The units 10A and 10C each comprise a disc 10F having a short central tube 106 from which radiate flow'channels 10H on both sides of the disc. The channels are open atthe periphery of the unit and communicate one with another by gaps 11. An annulus 11A on each side of the unit packs is provides a seating for the adjacent filter packs. The unit 103, shown more particularly in FIGURES l5 and 16,

differs from the units 10A and 10C in that the channels open into a central hole 11B and are "closed by a wall 11L at the periphery of the unit. Channel units 10 and 10D are identical and differ from the unit 10 B only, in that channels 11C are provided on one side only of 'a disc 11D, the disc of the unit 10 having a central hole 11E which aligns with the hole in the unit.10B and the bores of the tubes 106 of the units 10A and 10C,

The assembled channel units and filter packs are clamped between two plates 11F and 116 by bolts 11H which extend through the assembly. The plate 11F has a central hole 11] which aligns with the bores of the tubes 106. Also in the plate are radial holes 11K which communicate with alternate channels 11C in the unit 10.

The assembly may be located centrally within a casing 12 by an interior flange 12A which provides a seating for the plate 11F. Extending from the plate 11G is a rod 12B which passes through a central hole in the casing and which is threaded at its lower end for nuts 12C which when tightened clamp the assembly against the flange 12A. Fluid to be filtered enters the casing by way of a pipe 12D and flows into the open ends of the channels H in the channel units 10A and 10C through the adjacent filter packs 10E into the channels of the units 10, 10B and 10D and thence into the central conduit formed by the central holes and short tubes in the unit, some of the flow being by way of the radial holes in the plate 11F. Finally, the filtered fluid is discharged by way of a pipe 12E.

In order to prevent an accumulation of contaminant at the narrow ends of the channels 10H in the spacer units 10A and 10C, small gaps 11 may be provided between the walls of the channels and the central tube, through which gaps the contaminant may be dispersed.

The filter assembly previously described provides for four filter packs, but it is to be understood that any desired number of packs may be used together with channel units as required.

Referring to FIGURE 17 a filter pack is indicated at 14 having in-flow and out-flow lanes 14A and 14B respectively arranged in parallel. Connected to the inflow lanes are fluid supply pipes 14C and 14D having a main valve 14E and an exhaust valve 14F. Connected to the out-flow lanes is a fluid discharge pipe 146 having a main valve 14H. Cleansing fluid is supplied to the filter pack by way of a pipe 15 having a control valve 15A and an exhaust valve 15B.

In order to clean the filter pack, valves 14E and 14H are closed and valves 15A and 14F are opened. The cleansing fluid then flows through the filter pack and removes the contaminant which is discharged via the valve 14F.

If desired, a filter pack may be so arranged that gravitational force may be used so that the contaminant drops away from the flow passages.

Further, by'arranging that the flow of the fluid is across the flat surfaces of the laminae and by providing in-flow channels that are relatively shallow, say .005 inch, and by providing a width between the in-flow channels of at least as much as their own dimension, a very large area is provided on which contaminant may rest without causing blockage. This action is produced since the contaminant is free to move to the point of lowest velocity of the flow, and any pile up is pushed away from the points of higher velocity. Thus, a self-compensating clearing action is provided.

Again, by providing a large plain area around the inflow channels, percolation through the contaminant is practical, unlike the action of a gauze where very little depth of contaminant causes complete blockage.

I claim:

1. A filter for gaseous or liquid fluid comprising a pack of metallic laminae, each lamina having openings which are formed by an etching or electrolytic process, said openings constituting in-flow and out-flow lanes for the fluid, said in-flow lanes being reduced in cross sectional area adjacent the fluid entry ends of the inflow lanes, the arrangement providing for the interception of particles and prevention of clogging of the lanes.

2. A filter for gaseous or liquid fluid comprising a plurality of metallic laminae superimposed on one another to provide a pack; each lamina having means defining a plurality of regularly arranged openings therethrough; and each lamina, peripherally of said openings therethrough, being of substantially uniform thickness throughout; respective openings through alternate ones of said laminae partially coinciding throughout the thickness of the pack to define flow lanes proceeding in a thickness sense through the pack; respective openings through said laminae which are intermediate saidalteinate laminae also partially coinciding throughout the thickness of the pack to define flow lanes proceeding in a thickness sense through the pack, the flow lanes through the intermediate laminae being laterally otfset from the flow lanes through the alternate laminae; at least some of the openings through the alternate laminae also partly coinciding with at least some of the openings through the intermediate laminae to define lateral flow passages connecting at least some of the flow lanes through alternate laminae with at least some of the flow lanes through the intermediate laminae; a first masking plate presented facewise against one face of the pack of laminae closing off one end of each of the flow lanes through the intermediate laminae, said first masking plate having means defining openings therethrough in a thickness sense and communicating with the flow lanes through the alternate laminae; and a second masking plate presented facewise against the opposite face of the pack of laminae closing ofi one end of each of the flow lanes through the alternate laminae, said second masking plate having means defining openings therethrough in a thickness sense and communicating with the flow lanes through the intermediate laminae.

3. A filter for gaseous or liquid fluid comprising at least one pack composed of metallic laminae, each lamina of the pack having equally spaced openings formed by an etching or electrolytic process, flat bars between the openings constituted by portions of the laminae, said bars extending across the openings in alternate laminae of the pack to form at least two flow lanes in respect of each opening in said alternate laminae, said flow lanes extending through the thickness of the pack, laterally extending spaces between the bars of alternate laminae forming flow passages, and an apertured masking plate at each of two opposite sides of the pack, the apertures in one of said plates communicating with alternate flow lanes in the adjacent side of the pack and the apertures in the other of said plate communicating with the flow lanes intermediate the said alternate flow lanes at the adjacent and other side of the pack, the arrangement being such that the fluid to be filtered enters the flow lanes opening into one of said sides of the pack, through the said lateral passages and out through the flow lanes opening into the other of said sides of the pack.

4. A filter as set forth in claim 3, wherein the openings of alternate laminae are rectangular in shape, and wherein the openings in the laminae intermediate the said alternate laminae are of different shape, the assembly of the laminae providing flow lanes in the thickness of the assembly and lateral flow passages between coinciding portions of alternate laminae, the said passages communicating with the flow lanes to provide inlet and outlet channels for the fluid.

5. A filter for gaseous or liquid fluid comprising at least one pack composed of metallic laminae, each lamina of the pack having equally spaced openings formed by an etching or electrolytic process, flat bars between the openings constituted by portions of the laminae, said bars extending across the openings in alternate laminae of the pack to form at least two flow lanes in respect of the openings in said alternate laminae, said flow lanes extending through the thickness of the pack, laterally extending spaces between the bars of alternate laminae forming flow passages, an apertured masking plate at each of two opposite sides of the pack, the apertures in one of said plates communicating with alternate flow lanes in the adjacent side of the pack and the apertures in the other of said plates communicating with the flow lanes intermediate the said alternate flow lanes at the adjacent and other side of the pack, and a mounting and clamping device for the packs, the device comprising a grid for each pack, means for clamping; the packs to their respective grids, and means whereby the device may be fittedin a vessel. -6.' A filter as set forth in claim 5, wherein each grid comprises spaced bars each greater in width than in thickness, 'the bars being so arranged that their narrow sides face the direction of the flow ofithe fluid. 7. -A filter for gaseous or liquid fluid comprising at least one pack of metallic laminae, each lamina being circular and having perforations therein formed by an etching or electrolytic process, the perforations in alternate 1 laminae being of different shape to those of th elaminae intermediate the said alternate laminae, the perforations in'the said alternatelaminae and those in the intermediate laminae coinciding respectively to form flow lanes through the thickness 'of' the pack, and'fla't' bars between the perforations constituted by portions of the laminae, the bars of alternate laminae defining lateral flow passages communicating with the flow lanes, and an apertured maskingplat e at each 'of two opposite sides of the pack, the apertures in one of said plates communicating with alternate flow lanes in the adjacent side of th'epack and the apertures in the other of the plates communicating 8 V with the flow lanes intermediate, the saidalternatellow lanes at the adjacent and other .side of the pack. I 8. A filteras. set forth in'claim-V7 including amounting and clamping device; adapted to fit in a vessel, said device comprising. at least one circular plate having out;

wardly' extending passages .on e ach of its opposite sides and means whereby a circular .filter pack may be clamped to at least one side of the plate. w 7 I 7 References Cited 7 I UNITED STATES PATENTS V 1,694,939

12/1928 Heftler 21 0"+4-9z X 1,793,583; 2/1931 Bowd'en "21'0 4ssx 1,977,174 10/1934 Crawfordf z 1"0- -492 2,365,525 12/1944 CoX. V v V ,44 ,797 8/1948 Cox 21 x 2,581,337; 1/1952 Lapik FOREIGN PATENTS 7/1953 France. 7 w 4/ 19 60 Great Britain.

6/1960 Great Britain:

REUBEN FRIEDMAN, Primary Examiner. V

1). RIESS, Assistant Examiner. 

